Theme App Extension – “Unknown tag 'schema'” error during app preview

Hi everyone,

I’m getting the following error from Shopify’s side during shopify app preview, even though the build succeeds:

Is {% schema %} completely unsupported in all theme app extension block .liquid files?
Is this validation expected to fail only during app preview (even if local build passes)?
Are there any edge cases where schema inside block liquid is allowed, or must it always be moved to .json?
Any confirmation or official reference would be really helpful.
Thanks!

They just have broken something.
Check this post for updates: